A conventional door opening and closing mechanism in which a door to be attached to a body having an opening is separated from, and made in contact with the periphery of the opening so that the opening is opened and closed has been disclosed in Patent Document 1. This door opening and closing mechanism has a structure in which: the door is attached to the body so as to freely pivot and a handle is shaft-supported on the door. The handle has an operation portion to be held and operated by the user, and the end portion of the handle on the side opposite to the operation portion with respect to the rotation axis is placed face to face with the periphery of the opening. When the operation portion is pulled to allow the handle to pivot, the end portion is pressed against the body through the principle of a lever. Thus, the door is separated from the periphery of the opening with a predetermined distance even by a small operation force, and by further pulling the operation portion, the door is allowed to pivot and opened.    Patent Document 1: JP-A-2000-18803 (pages 2-3, FIG. 3)